BRIDGEPORT -- The executive director of the city's housing authority resigned Monday, ending a tensure of nearly eight years that saw the agency improve from "troubled" to being the recipient of national awards.

In an email to employees of the Bridgeport Housing Authority, Dulce Nieves, chairwoman of the agency's board of commissioners, said Executive Director Nicholas Calace had resigned effective May 31, although he would leave his post immediately. Information was not available Monday on the details of that arrangement.

The email did not indicate how the board would replace Calace, only that any matters pertinent to the office of executive director should now be directed to Nieves.

Calace took over the housing authority in the summer of 2005 from Robert Graham, an interim executive director who city officials at the time credited with beginning the turnaround of the agency in his nine months there.

The designation came after the BHA's previous director was fired, the agency's board of directors was replaced and a federal investigation was opened into allegations of misuse of funds and general mismanagement.

But about 18 months into Calace's tenure as executive director, he saw the BHA removed from HUD's list of troubled agencies. The improvement saved the housing authority from a decrease in funding and falling under federal control.

Last year, the agency received national recognition for its Bridgeport Housing First program, which provides homeless families with housing and other services.

According to the authority's website, the program won the National Award of Excellence, one of only six handed out annually by the National Association of Housing and Redevelopment Officials.

In her email to BHA employees, Nieves wished Calace well and offered appreciation for his "eight years of faithful service."